frontend: add whois client for more complex whois lookup

frontend/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:buster AS step_0
+FROM golang AS step_0
 ENV CGO_ENABLED=0 GO111MODULE=on
 WORKDIR /root
 COPY . .
@@ -6,6 +6,23 @@ RUN go build -ldflags "-w -s" -o /frontend
 
 ################################################################################
 
-FROM scratch AS step_1
+FROM alpine:edge AS step_1
+
+WORKDIR /root
+RUN apk add --no-cache build-base pkgconf perl gettext
+
+RUN wget https://github.com/rfc1036/whois/archive/refs/tags/v5.5.18.tar.gz \
+    -O whois-5.5.18.tar.gz
+RUN tar xvf whois-5.5.18.tar.gz \
+    && cd whois-5.5.18 \
+    && make -j4 LDFLAGS="-static" \
+    && strip /root/whois-5.5.18/whois
+
+################################################################################
+
+FROM scratch AS step_2
+ENV PATH=/
+ENV BIRDLG_WHOIS=/whois
 COPY --from=step_0 /frontend /
+COPY --from=step_1 /root/whois-5.5.18/whois /
 ENTRYPOINT ["/frontend"]